<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="https://cdn.bootcss.com/vue/2.5.18-beta.0/vue.js"></script>

</head>
<body>
    <div id="app">
        <p @click = "handleClick">{{sum}}</p>
    </div>
    <script>
        var vm = new Vue({
            el:"#app",
            data:{
                num1:10,
                num2:20
            },
            computed:{
                sum:{
                    get(){
                        return this.num1+this.num2
                    },
                    /* sum值改变的时候触发set方法 */
                    set (value){
                        var arr = value.split(" ");
                        this.num1 = arr[0]+"num1";
                        this.num2 = arr[1]
                    }
                }
            },
            methods:{
                handleClick(){
                    this.sum="w d";
                }
            }
        })
    </script>
</body>
</html>